SYNTHESIS OF DIAMOND FROM METHANE AND NITROGEN MIXTURE

We have found that diamond can be synthesized from a mixture of CH4 and N2 without adding any H-2. This new synthesis is sharply different from the common practice of diamond growth by chemical vapor deposition, which uses a hydrogen-rich mixture of CH4 and H-2. In this new approach, nitrogen becomes an active component of microwave plasma leading to diamond growth. Nitrogen participates in abstraction of hydrogen from the diamond surface. We hypothesize that formation of HCN is an indication of hydrogen abstraction that allows diamond to grow from CH4+N2 mixtures. As a consequence of surface processes, the crystal structure of the grown diamond is distorted. The sequence of tetrahedral layers is mixed (cubic and hexagonal) and it suffers from turbostatic disorder. Diamond films were characterized by x-ray diffraction, Auger electron spectroscopy, x-ray photoelectron spectroscopy, and Raman spectroscopy.